Re: need a sample code
From: emb in linux (haranath.t_at_gmail.com)
Date: 11/11/05
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Date: 10 Nov 2005 22:00:58 -0800
emb in linux wrote:
hi
using fgets i am able to do that.
> hi
> i am able to read and write a string from and to com-ports and i am
> unable to read a muti strings(sentence).how can i do that?
> thanks in advance.
>
> with
> regards
> emb
> in linux
> Alain Mosnier wrote:
> > Hi,
> >
> > emb in linux wrote:
> > > hai all
> > > This is my first post to this group.I am very much new to embedded
> > > programming .Now i want to write data to com1 and want to read from
> > > com2 .Here i have connected a NULL-MODEM cable in between the two
> > > serial ports.
> > > The following is the code,which i am running on my Linux Box.
> > > I am getting the return value from read as -1.
> >
> > I haven't analyzed your code, but hereafter you will find an example
> > that works for me. I have separated the sending and the receiving parts
> > in two separate processes, each with its own source file and binary. I
> > start the receiving part first, and it receives the character from the
> > sending part when I start it later on.
> >
> > Good luck,
> >
> > Alain
> >
> > Sending part:
> >
> > #include <stdio.h> /* Standard input/output definitions */
> > #include <string.h> /* String function definitions */
> > #include <unistd.h> /* UNIX standard function definitions */
> > #include <fcntl.h> /* File control definitions */
> > #include <errno.h> /* Error number definitions */
> > #include <termios.h> /* POSIX terminal control definitions */
> >
> >
> > int
> > main()
> > {
> > int fd; /* File descriptor for the port */
> > struct termios options;
> >
> > /*
> > * Open the first serial port, read/write, no controlling terminal,
> > * not care about the Data Carrier Detect signal
> > */
> > fd = open("/dev/ttyS0", O_RDWR | O_NOCTTY | O_NDELAY);
> > if (fd == -1)
> > {
> > /*
> > * Could not open the port.
> > */
> > perror("Unable to open /dev/ttyS0\n");
> > }
> > else {
> > /*
> > * Set all flags to 0 for the read call to be blocking!???
> > * (according to "Serial Programming Guide for POSIX Operating Systems")
> > */
> > fcntl(fd, F_SETFL, 0);
> >
> > /*
> > * Get the current options for the port...
> > */
> > tcgetattr(fd, &options);
> >
> > /*
> > * Set the baud rates to 115200...
> > */
> > cfsetispeed(&options, B115200);
> > cfsetospeed(&options, B115200);
> >
> > /*
> > * Enable the receiver and set local mode...
> > */
> > options.c_cflag |= (CLOCAL | CREAD);
> >
> > /*
> > * Set the option for 8N1
> > */
> > options.c_cflag &= ~PARENB;
> > options.c_cflag &= ~CSTOPB;
> > options.c_cflag &= ~CSIZE;
> > options.c_cflag |= CS8;
> >
> > /*
> > * Set the option for raw input
> > */
> > options.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
> >
> > /*
> > * Set the option for raw output
> > */
> > options.c_oflag &= ~OPOST;
> >
> > /*
> > * Set the new options for the port...
> > */
> > tcsetattr(fd, TCSANOW, &options);
> >
> > if (write(fd,"A",1)<0)
> > fprintf(stderr,"Write() of 1 byte failed!\n");
> > close (fd);
> > }
> >
> > return (0);
> > }
> >
> >
> > Receiving part:
> >
> > #include <stdio.h> /* Standard input/output definitions */
> > #include <string.h> /* String function definitions */
> > #include <unistd.h> /* UNIX standard function definitions */
> > #include <fcntl.h> /* File control definitions */
> > #include <errno.h> /* Error number definitions */
> > #include <termios.h> /* POSIX terminal control definitions */
> >
> >
> > int
> > main()
> > {
> > int fd; /* File descriptor for the port */
> > char *c;
> > struct termios options;
> >
> > /*
> > * Open the first serial port, read/write, no controlling terminal,
> > * not care about the Data Carrier Detect signal
> > */
> > fd = open("/dev/ttyS1", O_RDWR | O_NOCTTY | O_NDELAY);
> > if (fd == -1)
> > {
> > /*
> > * Could not open the port.
> > */
> > perror("Unable to open /dev/ttyS1\n");
> > }
> > else {
> > /*
> > * Set all flags to 0 for the read call to be blocking!???
> > * (according to "Serial Programming Guide for POSIX Operating Systems")
> > */
> > fcntl(fd, F_SETFL, 0);
> >
> > /*
> > * Get the current options for the port...
> > */
> > tcgetattr(fd, &options);
> >
> > /*
> > * Set the baud rates to 115200...
> > */
> > cfsetispeed(&options, B115200);
> > cfsetospeed(&options, B115200);
> >
> > /*
> > * Enable the receiver and set local mode...
> > */
> > options.c_cflag |= (CLOCAL | CREAD);
> >
> > /*
> > * Set the option for 8N1
> > */
> > options.c_cflag &= ~PARENB;
> > options.c_cflag &= ~CSTOPB;
> > options.c_cflag &= ~CSIZE;
> > options.c_cflag |= CS8;
> >
> > /*
> > * Set the option for raw input
> > */
> > options.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
> >
> > /*
> > * Set the option for raw output
> > */
> > options.c_oflag &= ~OPOST;
> >
> > /*
> > * Set the new options for the port...
> > */
> > tcsetattr(fd, TCSANOW, &options);
> >
> > fprintf(stderr,"In server\n");
> > if (read(fd,c,1)<1)
> > fprintf(stderr,"Read() of 1 byte failed!\n");
> > else
> > fprintf(stderr,"Received %c\n",*c);
> > close (fd);
> > }
> >
> > return (0);
> > }
> >
> > /*
> > * seriser
> > * 2005, Alain Mosnier
> > */
> >
> > #include <stdio.h> /* Standard input/output definitions */
> > #include <string.h> /* String function definitions */
> > #include <unistd.h> /* UNIX standard function definitions */
> > #include <fcntl.h> /* File control definitions */
> > #include <errno.h> /* Error number definitions */
> > #include <termios.h> /* POSIX terminal control definitions */
> >
> >
> > int
> > main()
> > {
> > int fd; /* File descriptor for the port */
> > char *c;
> > struct termios options;
> >
> > /*
> > * Open the first serial port, read/write, no controlling terminal,
> > * not care about the Data Carrier Detect signal
> > */
> > fd = open("/dev/ttyS1", O_RDWR | O_NOCTTY | O_NDELAY);
> > if (fd == -1)
> > {
> > /*
> > * Could not open the port.
> > */
> > perror("Unable to open /dev/ttyS1\n");
> > }
> > else {
> > /*
> > * Set all flags to 0 for the read call to be blocking!???
> > * (according to "Serial Programming Guide for POSIX Operating Systems")
> > */
> > fcntl(fd, F_SETFL, 0);
> >
> > /*
> > * Get the current options for the port...
> > */
> > tcgetattr(fd, &options);
> >
> > /*
> > * Set the baud rates to 19200...
> > */
> > cfsetispeed(&options, B115200);
> > cfsetospeed(&options, B115200);
> >
> > /*
> > * Enable the receiver and set local mode...
> > */
> > options.c_cflag |= (CLOCAL | CREAD);
> >
> > /*
> > * Set the option for 8N1
> > */
> > options.c_cflag &= ~PARENB;
> > options.c_cflag &= ~CSTOPB;
> > options.c_cflag &= ~CSIZE;
> > options.c_cflag |= CS8;
> >
> > /*
> > * Set the option for raw input
> > */
> > options.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
> >
> > /*
> > * Set the option for raw output
> > */
> > options.c_oflag &= ~OPOST;
> >
> > /*
> > * Set the new options for the port...
> > */
> > tcsetattr(fd, TCSANOW, &options);
> >
> > fprintf(stderr,"In server\n");
> > if (read(fd,c,1)<1)
> > fprintf(stderr,"Read() of 1 byte failed!\n");
> > else
> > fprintf(stderr,"Received %c\n",*c);
> > close (fd);
> > }
> >
> > return (0);
> > }
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